A lateral flow assay (LFA) can be a paper-based device that detects a presence of an analyte in a sample. LFAs are a common point of care diagnostic tool. LFAs function by wicking (e.g., capillary action) a sample of interest through a porous membrane (e.g. paper) where chemical reactions can occur in and on the surface of the porous membrane. The LFA can contain a conjugate material therein. Conjugate materials are typically formulated to provide the solvent(s) and reactant(s) necessary to dissolve, react, color, tag, or bond to the suspected analyte in a sample. Thus, if the analyte is present, the conjugate or a component thereof will react with the analyte in the sample. The conjugate material can include an indicator material configured to provide indication of a presence of the analyte, a reacted analyte, or an analyte-conjugate complex. Typically, the readout of an LFA can be a visual change at some point along a length of the LFA. Many LFAs include an analyte collection material near the distal end of the LFA whereby the analyte and any indicator particle bonded thereto are bound in large concentration to provide visual or other indication of a positive or negative result.
Systems incorporating photothermal spectroscopy assay readers can enhance the sensitivity of LFA and similar assay results beyond visual detection. A photothermal spectroscopy assay reader can detect radiation of heat from the surface of an LFA saturated with the sample of interest. The conjugate material reacted with analyte in the sample can absorb energy from the light. The photothermal spectroscopy assay reader can detect a thermal response from the irradiated conjugate material on the surface of the LFA, which can provide an indication of the presence of the analyte.
Manufacturers and users of photothermal spectroscopy assay readers and LFAs continue to seek photothermal spectroscopy assay readers and LFAs with improved detection capability.